# http://www.wellho.net/resources/ex.php4?item=y115/penv.py

import os

def main(env_key=''):

    res = {}
    for param in os.environ.keys():
        #print "%20s %s" % (param, os.environ[param])
        res[param] = os.environ[param]

    if env_key == '': return res
    else:
        if res.has_key(env_key):
            return res[env_key]
        else:
            return ''

if __name__=='__main__':
    
    print main('USERNAME')